The present invention relates generally to interface devices between humans and computers, and more particularly to computer interface devices that provide force feedback to the user.
Computer systems are used extensively in many different industries to implement computer controlled simulations, games, and other application programs. More particularly, these types of games and simulations are very popular with the mass market of home consumers. A computer system typically displays a visual environment to a user on a display screen or other visual output device. Users can interact with the displayed environment to play a game, experience a simulation or virtual reality environment, or otherwise influence events or images depicted on the screen. Such user interaction can be implemented through the use of a human-computer interface device, such as a joystick, xe2x80x9cjoypadxe2x80x9d button controller, mouse, trackball, stylus and tablet, or the like, that is connected to the computer system controlling the displayed environment. The computer updates the simulation or game in response to the user""s manipulation of an object such as a joystick handle or mouse, and provides feedback to the user utilizing the display screen and, typically, audio speakers.
In some interface devices, tactile and/or haptic feedback is also provided to the user, more generally known as xe2x80x9cforce feedback.xe2x80x9d These types of interface devices can provide physical sensations to the user manipulating a user manipulable object of the interface device. For example, the Force-FX controller from CH Products, Inc. and Immersion Corporation may be connected to a computer and provides forces to a user of the controller. Typically, motors or other actuators are coupled to the user object and are connected to the controlling computer system. The computer system can provide forces on the object in conjunction with simulation/game events by sending control signals to the actuators. The computer system can thus convey physical force sensations to the user in conjunction with other supplied feedback as the user is grasping or contacting the object of the interface device. Force feedback interface devices can thus provide a whole new modality for human-computer interaction.
Force feedback input/output (I/O) devices of the prior art have concentrated on providing maximum haptic fidelity, i.e., the realism of the tactile feedback was desired to be optimized. This is because most of the force feedback devices have been targeted at the specific needs of highly industrial applications, and not a mass consumer market. To attain such realism, mass market design concerns have been sacrificed in the prior art.
One consumer market design concern that is always present in force feedback devices is the size, weight, and power consumption of actuators included in the device. To provide realistic high magnitude forces, large and heavy actuators have necessarily been used in non-mass-market force feedback devices of the prior art. However, in the consumer market, such large and heavy actuators are a major drawback, since consumers would prefer a portable, small interface device that can easily fit on a desktop or other small working space. Even more significantly, such large actuators prevent producing a force feedback interface device at a low enough cost to be acceptable to mass market consumers. In the prior art, however, smaller actuators were not an option if realistic forces were to be presented to the user.
Some mass market force feedback devices of the prior art, nevertheless, have been provided, and these devices typically include small actuators to reduce costs. However, force feedback devices with small actuators have a problem in that they may not allow the superposition of many types of force effects due to a limited dynamic range available from the actuators. For example, if a jolt feel sensation is desired to be superimposed on a vibration feel sensation to the user, then the force magnitudes of the two feel sensations are added together. However, if the maximum available dynamic range of the actuators is small, as is typically the case for mass market force feedback devices, then the realism of the feel sensations must be sacrificed in some way to accommodate both feel sensations. For example, the jolt sensation would have to be reduced in magnitude, thus reducing the effectiveness of that feel sensation to the user. Providing actuators with a greater dynamic range typically means providing larger, more expensive actuators, which is not usually feasible in the consumer market as explained above.
In addition, there is unnecessary complexity in the manipulation of force feedback signals in the prior art. To produce a feel sensation to a user of the force feedback device, a force signal of the prior art must include all information required to realistically output that feel sensation to the user. However, the computational burden of providing feel sensations to a user can be high, especially when providing multiple simultaneous feel sensations. To adequately provide the desired forces, complex and expensive components typically must be included in the force feedback device, often pushing the cost of realistic force feedback out of the reach of mass market consumers.
The present invention is directed to providing and controlling force feedback to a user operating a human/computer interface device. Impulse-shaped force signals are provided to reduce the necessary force output from the actuators, thereby allowing smaller, less complex forces to be generated for the user with minimal reduction in the realism of generated forces.
More particularly, a method of the present invention for generating a force signal for creating a feel sensation upon a user through a force feedback device includes providing a source wave. A set of control parameters are provided to define the source wave that include at least one of a steady-state magnitude value representing a steady-state magnitude of the source wave, a frequency value representing a frequency of the source wave, and a duration value representing a duration of the feel sensation. Further, a set of impulse parameters is provided to modify the source wave, including an impulse value specifying an impulse force level of the source wave applied to the user and a settle time representing a time required for a magnitude of the force signal to change from the impulse value to the steady-state magnitude value. Finally, using a processor, the force signal is formed from the source wave and the sets of control parameters and impulse parameters. Preferably, the feel sensation is generated as physical forces produced by actuators on the force feedback device in response to the force signal. Preferably, the force signal is initially provided at the impulse value and is then decayed to the steady-state magnitude value after an expiration of the settle time. The steady-state magnitude value is lower than a magnitude value of a non-impulse-shaped force signal required to create a corresponding feel sensation having a similar apparent sensation to the user. Thus, by generating the feel sensation using the steady-state magnitude value, less power is consumed than if said non-impulse shaped force signal were used.
Optionally, a set of application parameters specifying a vector of application for the force signal, and a set of trigger parameters specifying how the feel sensation should be generated responsive to an activation of a button of said force feedback device can also be provided for the source wave. In some embodiments, a host processor of a host computer system provides the impulse-shaped force signal. In other embodiments, a local processor is provided local to the force feedback device for provided and/or relaying the impulse-shaped force signal to actuators. The control parameters and impulse parameters can be provided to the local processor by the host processor. The host processor implements a simulation in parallel with said local processor controlling said actuators. An apparatus of the present invention similarly provides a user object movable by a user, a sensor for detecting a position of the user object, a local microprocessor, separate from said host computer system and outputting an impulse-shaped force signal, and an actuator receiving the impulse-shaped force signal and applying a force having an impulse magnitude followed by a different steady-state magnitude to the user object.
A method of the present invention for generating xe2x80x9cconditionxe2x80x9d forces and xe2x80x9ceffectxe2x80x9d forces for creating feel sensations upon a user through a force feedback system includes generating the conditions using a local processor to reduce a workload of a host processor. The conditions represent force signals for creating feel sensations dependent on data regarding motion or position of the user manipulatable portion of the force feedback device. This motion or position data is received by the local processor by sensors of the force feedback device. The effects can be generated using the host processor and represent force signals for creating feel sensations not dependent on the motion or position of the user manipulatable portion of the force feedback device. Alternatively, the effects can be generated using the local processor, where the force signals are generated in response to commands and parameters from the host processor, thereby further reducing the workload of the host processor.
In another aspect of the present invention, force signal data is transmitted in a force feedback system. A first force signal data value and a second force signal data value are sent in a first data packet from a host processor to a local processor. The second force signal data value and a third force signal data value are sent from the host processor to the local processor, where the third value is different from the first and second values. The second data packet and first data packet are consecutive data packets such that the xe2x80x9coverlappedxe2x80x9d second force signal data value may be retrieved from either the first data packet or the second data packet if either the first data packet or the second data packet is unusable after the transmission. Preferably, the local processor disregards duplicate information represented in consecutive packets if both packets are successfully received by the local processor.
The present invention advantageously provides an impulse-shaped force signal that is used to provide feel sensations to a user manipulating a force feedback device. The force signal includes an impulse of high magnitude and a steady-state force following the impulse, which provides a realistic sensation of constant force without having to continuously output a high magnitude force. That is, the present invention advantageously manipulates only those variables (impulse and steady state) of the force signal that have a significant impact on the perception of the user, reducing the complexity of the required hardware and minimizing the computational burden of representing diverse feel sensations. In addition, the local processor technology reduces the computational burden from the host processor. Furthermore, the overlapping of data in force signal transmissions reduces the computation burden of checking for errors and handshaking with a sending device. These improvements allow a computer system to provide accurate and realistic force feedback using a low-cost force feedback device and is thus ideal for the mass market of home computer systems.
These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following specification of the invention and a study of the several figures of the drawing.